Image Processing Reference
In-Depth Information
Related (but probably necessary) stupidity persists in the way that computer DVD
disk drives are set up to control the regionalized playback with limited numbers of region
changes and abrupt lockouts, which render the drive inoperable.
18.15
Watermarking Techniques
Some content owners are realizing that their money is better spent on watermarking the
content so the original purchaser who allowed his or her copy to be compromised is trace-
able. The Recording Industry Association of America (RIAA) has already begun to use this
kind of legal tactic to pursue people who illegally downloaded and then shared music
tracks. People who offered up music archives for others to download wholesale were
effectively painting a large target on their forehead.
Closing the circle by adding a unique watermark when a track is downloaded from
iTunes or Napster is an optimal way of tracing pirated content. Virtually all the other DRM
mechanisms that prevent fair use could then be set aside because they are not going to
stop determined pirates.
Watermarking must be robust enough to remain intact throughout any compression
and transcoding process. It is feasible to bury an encoded version of the transaction record
in the sample data so that wholesale piracy can be tracked back to the original purchaser.
So if a pirate rips off a CD from iTunes or the video equivalent of it, there could still be
some traceable identifying data embedded within it.
It is a matter for conjecture whether such a scheme has or might be implemented in
the future. The service provider should never disclose the details of when or where it is
used. Indeed, the very fact that it is technically feasible should work in favor of the con-
tent owners because if people were made to believe that they could be traced, they might
be more circumspect in their willingness to pass on “free” copies of tracks they have
bought for their own personal use. In the end, a propaganda war may be more cost-effec-
tive than trying to reliably secure the content.
The Sarnoff Corporation has devised a watermarking scheme that is very resilient to
movies being duplicated, compressed, or even filmed with a handheld camera in the
movie theater. A digital signature is encoded into the movie and can be recovered to trace
back through the distribution chain and identify exactly where the compromise occurred.
This is especially useful for D-cinema applications.
In general, consumers instinctively know the difference between right and wrong.
A passive DRM system that helps to keep them honest is likely to be more useful in the
long term than a draconian technique that renders material unplayable in some devices.
18.15.1
Hiding the Crown Jewels in Plain Sight
In the end, the most practical way to secure content is to mark every copy indelibly with
some code that records a transaction identifier. That code can be used to trace back to
where the unauthorized copy was first duplicated. A few casual copyists will be very
alarmed to find that the copy they gave away to an old friend ended up being pressed on
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